Clasps for connecting together webs and straps are well known and widely used for such diverse applications as securing the two ends of a belt together, closing rucksacks and other bags and sacks, fastening coats and waterproofs and so on. The almost universally accepted design nowadays for such clasp consists of two parts secured to respective webs, one of the parts (the male part) consists of a pair of prongs, each having an outwardly extending barbed tooth and the other part (the female part) has a channel into which the prongs can be pushed. The width of the channel is smaller than the distance between the outsides of the prongs and so, as the male part is pushed into the channel, the prongs are flexed inwardly by the outer walls of the channel. The walls includes a pair of openings into which the barbed teeth can snap when the male part has been pushed sufficiently far into the channel. The engagement of the barbs in the channel wall openings retains the two parts together and so connects the webs attached to the two parts.
A guide prong is provided between the two barbed prongs in the male part of the clasp; the guide prong engages ridges in the channel of the female member to ensure that the male member travels axially along the channel.
In order to undo the clasp, the prongs are pinched to move towards each other thereby releasing the barbs from the openings and allowing the male part to be withdrawn from the female part.
Because the openings are exposed, it is possible for a user to catch his/her fingers between the barb and the opening, which can be painful.
U.S. Pat. Nos. 5,203,058, 5,735,024, EP-0305130 and GB 21116626 each describes a clasp or buckle for fastening straps having two identically-shaped parts; each part has a male prong and a female channel with the male prong of each part being arranged opposite to the female channel of the other part so that when the two parts are pushed together, the male prongs can engage in the respective female channels. The prongs have barbs that engage in openings in the channels to hold the buckle in a fastened condition. The barbs can be moved to disengage the barbs from the openings and so release the buckle. The two parts of the buckle, once the barbs are released, must be separated to open the buckle completely unless the tension in the straps is sufficient to pull the prongs out of the channels; however, if the tension is sufficient to pull the parts of the buckle apart, the same tension can make it difficult to release the prong barbs from the channel openings.
The present invention provides an alternative design of clasp where the two parts of a buckle separate from each other without the need for tension in the straps.